Railway-traffic-controlling apparatus



Aug. .19, 1930 P. N. BOSSART 1,773,297v

RAILWAY TRAFFIC CONTROLLING APPARATUS Filed Dec. 8. 1927 G 70 Tmfiflifle% I I 27 25 22 51 I I V.

I I 8 A, 11

INVENTOR".

- P.-/\/.B os sa Patented Aug 19, 193%) PAUL N. BOSSABT, OF SWISSVALE,PENNSYLVANIA, ASSIGNOR TO THE UNION SWITCH' & SIGNAL COMPANY, orgs'wIss'vALE, rn msYLvaNiA, a'eonroaarron or PENN- SYLVANIA aarnwamrnarrro oonrnoimme APnAaAT s Application filed December 8, 1927. Serial No. 238,548.

' diagrammatic view showing one formof ap- Fig. 2 is,

paratus embodying my invention. a diagrammatic view showing a modified i w form of the apparatus illustrated in Big. 1 and also embodying my invention.

' Similar reference characters refer to sinnlar parts in both views.

1 Referring first to Fig. 1, the reference character A designates a train carried receiver comprising a niagnetizable core B and a magnetizable bridging member C. In the form illustrated in the drawing the left-hand end 'of the core B is provided with a leg 3 eX- tending toward the left-hand end of the bridging member C but spaced therefrom by an air gap 4; Core :13 t :niinates in a pole member terminates in a pole o gpolei2 of core B;

2 adjacent the trackway. The core 1B is also providedwith a leg 5 adjacent the left-hand end of memberzC but spaced therefrom by an air gap 6. Furthermore, a leg 7 on core P extends toward the right-hand end of the member 0 but is spaced from the member by an air-gap 12. The right-hand'end of the Located on core B between legs 3. and 5 is a primary 1 which is constantly supplied with alternating current from a generator (Lthe circuit for thiswi-nding preferably but not necessarily includinga condenser 27 by means of'which the circuit is tuned to resonance at the frequency of the current supplied bythe generat0r,;G.L The member C carries a secondary 9 which is PlOVlClGdWliJll a c1rcu1t1ncluding the winding of a relay R and a front contact 11 of'thi's relay. The circuit for secondary 9 isalso preferably, but not necessarily, tuned to resonance, at the frequency of the current supplled by generatorG, by means o-fa condense 10. The relay B may be utilized in any suitable manner to control train carried governing means; as hereshown a similanto front contact 13 of this relay is included'in circuit with a battery 14: and a lamp 15 so that the lamp will be lighted when the relay is en ergized It will be observed that the flux created in core B by the current in primary 1 takes two paths, a portion of this flux traversing the path including leg 3, airgap 4 member C, air gap 6 and leg 5, and another portion of the flux travers ng a magnetic circuit includin the left-hand end of core B sole 2, the air gap between poles 2 and 8, member C, air gal-p12 and leg 7 The parts are so proportloned that the reluctances of those portions of the core'B and the member G which are included, in the circuits just de scribed form a comparatively insignificant party of the total reluctances of these circuits. It'will be plain, therefore, that the magnetie structure of the receiver A is analogousto the electric circuits well known to the Ell'u in the form of a lVheatst-onebridge, the air 1 and 6 formingtwo arms of the bridge. and

the air gap between poles 2 and 8' and the air gap 12 forming the other arms of thebridge.

Located in the trackway is a controlling element D comprising a magnetizable core 16 provided with a winding 17 The winding 17 is provided with a circuit including a reactor 19 and a condenser l8 and controlled by the front contact 20 of a relay J. The relay J mayin turn be controlled in any suitable manner and when this relay is energized the circuit is closed for winding 17 of element D, the parts being so proportioned that the reactances of 18 and 19 are substantially equal and opposite at the'frequency of the currentsupplied by genera-tor G; The element D is located adjacent the path of travel of the re ceiver A and is so, disposed that when the receiver passes over the element D, the core 16 is introduced in the air gap between the poles 2 and 8 of the receivers. The parts are so proportioned that if the circuit for winding 17 is open when the receiver A is over the 5 element 1), the ratio of the reluctances of 1115 gaps 4 and'6 isequal to the ratio of the freluctance of the path between poles 2 and 8 gap 12. This is the conditionfor balance of the magnetic bridge, that is to say, under 106 through the core 16 to the reluctance of air e &

these conditions the magnetic potentials of the two ends of the core C are equal so that there is substantially no flux linking the secondary 9. Under these conditions, therefore, no electromotivc force is induced in secondary 9 and relay R is de-energized. hen the receiver is not located over the element-D, the reluctance-of the path between poles 2 and 8 is considerably greater than when the core 16 is included. in this path and under these conditions the bridge is unbalanced so that the magnetic potentials at the two ends of the bridge member C are unequal and an alternating lux links secondary 9 to induce in this winding an electromotive force which is effective to supply to relay R a sufficient current to hold the relay in its energized condition. The path of the predominating or effective flux through secondary 9 under these conditions may be traced from primary 1 on core B, through leg 3, air gap 4;, member C, air gap 12, leg 7, and core B back to primary 1.

It is of course well known that eddy currents in the iron portions of the receiver A and the trackway element D will cause magnetomotive forces which are substantially out of phase with the magnetomotive force created by primary 1. The receiver and the trackway element should therefore be so proportioned that these quadrature magnetomet-ive forces in the separate arms of the mag netic bridge are in the same ratio as the reluctances of the air gaps so that there will be no electromotive force induced in secondary 9 when the receiver is over an element D having its winding 17 open circuited.

In explaining the operation of the apparatus, I will first assume that when the train passes over the trackway element D, the contact 11 of relay J is open, so that the circuit for winding '17 is open. Under these conditions the introduction of the core 16 with the magnetic path between poles 2 and 8, decreases the reluctance of this path to the value at which the bridge is balanced so that no flux links secondary 9 and relay It becomes de-energized to display a stop indication on the train. Inasmuch as the circuit for relay R includes a front contact 11 of this relay, the relay when once open, will remain open until the path through the front contact 11 is shunted. This shunting may be accomplished, for example, by a push button 21 connected in multiple with contact 11.

If contact 20 of relay J is closed when the train passes over the element D, the effect of this element on the train carried apparatus is neutralized to such an extent that the relay R remains closed, that is to say, when the circuit for winding 17 is closed, this winding practically nullifies the effect of the core 16 on the receiver A.

In actual practice, it is customary to locate the relay J at a considerable distance from the element D. Under these conditions, I prefer to locate the reactor 19 adjacent the relay J, and to locate the condenser 18 adjacent the core 16. Under these conditions if a short occurs between the wires extendingfrom the element D to the relay J, that is, if these wires become connected together, the circuit then closed for winding 17 will have a comparatively high impedance, and if a train passes'the element D, relay R will become de-energized.

I prefer to construct the reactor 19 with an-air core since its power factor, and hence the tuning of the circuit for winding 17 will be independent of the power supplied to the element D from the receiver A. The tuning of the circuit for winding 17 will then be independent of the spacing between the receiv er and the core 16 and will also be independent of the fluctuations in the electromotive force of generator G. The reactor. 19 should have alow power factor so that the total impedance of the circuit for windingv 17 will be low, and for the further reason that the condenser 18 will then have the greatest impedance for a given resistance of reactor 19 when the lead wires are shorted. An air core reactor having these characteristics-is easier to obtain than one having an iron core, particularly for use with higher frequencies of the order of those mentioned hereinafter.

It is obvious that train carriedreceivers of the type here shown will pass over masses of iron located in the trackway, such as the rails of cross-overs, etc. It is undesirable for such masses of iron to produce a stop indication on board the train and I therefore prefer to so construct the apparatus that it will distinguish 7 between control elements D located in the trackway and any other masses of iron which may be locatedadjacent .the path of travel of receiver A. It is, of course,

well known that the permeability of iron is a function of the intensity'of the magnetic field. The permeability of air, however, is independent of the field strength and I therefore propose to supply a comparatively small current to the primary 1 so that the magnetic field will be comparatively weak. Under these conditions, the permeability of the iron cores B and 16 and of the member C will be near the value of the initial permeability for the material and the reluctance of the core 16 will comprise a considerable part of the total reluctance of the magnetic path between poles 2 and 8 and including this core. In one embodiment of my invention, I have discovered that with a magnetomotive force of approximately 10 ampere turns supplied by primary 1, it is possible to construct the receiver A and the element D in such manner that the reluctance of the core 16 amounts to approximately 10% of the total reluctance of the magnetic circuit including core B,

comprising a train carried receiver having a source of magnetomotiveforce, a first magnetic circuit including said source and'a first and second airgaps,.a second magnetic circuit including said source and a third and v.fourth air gaps, a magnetizable member connecting a-point in said first circu t between the first and second air gaps with a point in the second circuit between the third and fourth a11- gaps, governing means responsive to the flux througlrsaid member, and vmeans lOCZLtGdlll the trackway for at times changing the reluctance of one of said air gaps to such-a value thatthe ratio of the reluctances of the first and second air gaps 18' substantially equal to the ratio of the reluctances of'the-third and fourth air gaps.

3. Railway. traflic controlling apparatus comprising artrain carried receiver having a source of magnetomotive force, a magnetic bridge having a first and a second arms supplied with flux from said source, a third and a fourth arms supplied with flux from said source, amagnetizable member connecting the commonpoint of said first andsecond arms with the, common point of'the third and fourth arms, means located in the track- Way for at-times ,varying the ratio of the reluctances of the-third and fourth arms, and governing means responsive to the flux insaid member. I I

4. Railway trafiic controlling apparatus comprising a train carried receiver having a source of magnetomotive force, a magnetic bridge having a first and a second arms supplied with fluxfromsaid source, a third and a fourth armssuppliedwith flux from said source, a magnetizable member connecting the common point ofsaid first and second arms with the common point of the third and fourth arms, means located in the trackway for co-operating with said receiver at times to vary the reluctance of one of said arms so that the ratio of the reluctanc-es of thefirst and second arms equals the ratio of 1 the third and fourth arms, and governing means responsive to the flux in said member.

5. Railway trafiic controlling apparatus comprising a train carried receiver having a source of magnetomotive force, a magnetic bridgehaving a first and a second arms supplied with flux from said source, a third and a fourth arms supplied with flux from said source, a magnetieable member connecting the common ;point of saidfirst and second arms with the common point of the third and fourth arms, means located in the'trackway for co-operating with said receiver at times to vary the reluctance ofone of said arms so that the ratio of the reluctance of the first and second arms equals the ratio of the third and fourtharms, a winding on said bridging member, and governing means controlled by said winding.

6. Railway trafiic controlling apparatus comprising a train carried receiver having a magnetizable core, a source of magnetomotive force on said core, a magnetizable bridging member having one end spaced from said core by two air gaps and having the other end spaced from the core by two other air gaps, a winding on said bridging member, governing means controlled by said winding, means located in the trackway to at times vary the reluctance of one only of said air gaps to a value for which no electromotive forceis induced in said winding, and governing means controlled by said winding.

7. Railway trafiic controlling apparatus comprising a train carried receiver having a source of magnetomotive force, a magnetic bridge having a first and a second arms supplied with fluX from said source, a third and a fourth arms supplied with flux from said source, a magnetizable member connecting thecommon point of said first and second armswith the common point of the third and fourth arms, means located in the trackway for co-operating with said receiver at times to vary the reluctance of one of said arms. so that the ratio ofthe reluctance of the first and second arms equals the ratio of the third and fourth arms, a winding on said member, a relay receiving energy from said winding, a rectifier interposed between said relay and said winding, and governing means controlled by said relay.

8. In combination, a train carried receiver comprising a magnetizable member, a source of magnetomotive forcerof the order of ten ampere turns associated with said member, a winding on the. member, an amplifier having its input terminals receiving energy from said winding, governing means on the train receiving energy frointhe output terminals of said amplifier, and a magnetizable core of high initial permeability located in the trackway adjacent the path of travel. of said receiver and co-o-perating therewith to at times vary the flux through said winding.

- 9. In combination, a train carried receiver comprising a magnetizable member having a primary and a secondary, means for supplying the primary with alternating current V at a frequency of the order of one thousand cycles per second and of such value as to create a magn'etomotive force of the order of ten ampere turns, an amplifier receiving energy-from said secondary, a direct current relay receiving energy from said amplifier, a

- rectifier interposed between said amplifier and said relay, and a'laminated iron core of high initial permeability located in the trackway adjacent the path of travel of said receiver and cooperating therewith to at times vary the flux through said secondary. In testimony whereof I afiix my signature.

PAUL N. BOSSART. 

